Concentrated silicone antifoam emulsion

Abstract

The present invention relates to concentrated silicone-in-water antifoam emulsions, their preparation and methods for controlling foam.

Description

[Technical field]

[0001] The present invention relates to the field of silicone-based antifoam agents. More specifically, the present invention relates to a handleable, dispersible, storage stable and effective concentrated silicone-in-water antifoam emulsion. The present invention also relates to a method for producing the non-viscous concentrated antifoam emulsion and a method for using the concentrated antifoam emulsion to inhibit foam formation. [Background technology]

[0002] Foams are dispersions of gas bubbles in a liquid or solid matrix. Surfactants and surface agents, such as detergents, wetting agents, emulsifiers or dispersants, are commonly used in various industries to lower the surface tension of the liquid, reduce the tendency of accumulation at the gas-liquid interface due to their amphiphilic nature, retard the coalescence of the gas bubbles, and thus stabilize the foam.

[0003] Antifoam compositions are systems that, when added to a foaming liquid, promote foam collapse versus foam formation. Typically, these compositions are added at low concentrations. Antifoams are applied in a wide variety of manufacturing and treatment processes, including paints and latexes, coating processes, textiles, fermentation processes, polymer manufacturing, cleaning compounds, pulp and paper, wastewater treatment, and cooling towers.

[0004] The addition of silicone antifoam compositions has proven to be particularly effective in controlling foam. Silicone antifoam compositions are hydrophobic particles such as silica dispersed in a silicone matrix. U.S. Pat. No. 3,383,327 describes a composition containing silica dispersed and heated in polydimethylsiloxane.

[0005] To obtain improved antifoam performance, the polydimethylsiloxane can be partially replaced with a branched polymer or a three-dimensional network.

[0006] For this purpose, EP-A-0163541 describes a method for producing silicone defoamers by polycondensation reaction at a given temperature with reactive organopolysiloxanes containing hydroxyl or alkoxy groups in the presence of a catalyst, a silicone resin, a filler and a non-reactive organopolysiloxane. Furthermore, EP-A-2794760 describes a method for producing silicone defoamers at a given temperature from a mixture of reactive organopolysiloxanes containing hydroxyl groups, two types of silica, hydrophobic and hydrophilic, respectively, and a silicone resin in the presence of a catalyst. Here too, a polycondensation reaction is used. EP-A-0434060, US-A-8053480 and WO 2021 / 167728 describe silicone defoamers obtained by polyaddition chemistry. WO 2020 / 108750 and WO 2020 / 108751 combine polyaddition and polycondensation chemistries. Irradiation chemistry using high-energy radiation is also described in WO 2021 / 126195.

[0007] However, these silicone defoamers can have undesirable viscosities for their use and are difficult to disperse in aqueous media. In addition, they can exhibit viscoelastic behavior, also known as the Weissenberg effect. This effect is a manifestation of the normal non-zero stress differences typical of certain polymer solutions (viscoelastic fluids). This phenomenon is manifested by the liquid climbing up a rotating rod immersed in such a viscoelastic fluid. Therefore, they are formulated as silicone-in-water emulsions by adding emulsifiers.

[0008] Various compositions are described for obtaining silicone antifoam emulsions. For example, WO 2016 / 107987 describes a method for producing silicone droplets in water with silicone content limited to 10% by weight. Higher concentrations are described in WO 1998 / 000216, whose examples consist of emulsions with a solids content of 35%. The emulsification of silicone antifoams often requires the use of certain surfactants, such as sorbitan esters cited in WO 1998 / 000216 and WO 2016 / 107987, which inhibit silicone antifoams from breaking down the interfacial layer of the emulsion.

[0009] For reasons of productivity and environmental design, it is increasingly desirable to increase the concentration of silicone in silicone antifoam emulsions by limiting the concentration of water.However, it is well known in the field of emulsions that the viscosity increases significantly when the volume fraction of droplets increases.When the concentration is increased, the emulsion changes from Newtonian behavior to non-Newtonian pseudoplastic behavior, making it very difficult to handle, pour, pump and disperse.

[0010] In this context, there is a need, firstly, for emulsions of silicone antifoam agents with high viscosity or viscoelastic properties, which contain high concentrations of silicone while maintaining a low emulsion viscosity, typically below 6000 mPa·s, preferentially below 3500 mPa·s, and which have good storage stability, and, secondly, for emulsions of silicone antifoam agents which must be water-dispersible, in the sense that their antifoam performance must not be affected by the species used for emulsification, in order to ensure the availability of the active moieties at the liquid-gas interface. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Pat. No. 3,383,327 [Patent Document 2] European Patent Application Publication No. 0163541 [Patent Document 3] European Patent Application Publication No. 2794760 [Patent Document 4] European Patent Application Publication No. 0434060 [Patent Document 5] U.S. Patent No. 8,053,480 [Patent Document 6] International Publication No. 2021 / 167728 [Patent Document 7] International Publication No. 2020 / 108750 [Patent Document 8] International Publication No. 2020 / 108751 [Patent Document 9] International Publication No. 2021 / 126195 [Patent Document 10] International Publication No. 2016 / 107987 [Patent Document 11] International Publication No. 1998 / 000216 Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, an object of the present invention is to satisfy at least one of the following objectives.

[0013] One object of the present invention is to provide a silicone antifoam emulsion which simultaneously meets these demands, i.e., a high concentration of silicone while retaining low viscosity, dispersibility, and storage stability, and which has good antifoam properties.

[0014] Another essential object of the present invention is to provide a method for producing a silicone antifoam emulsion, the resulting emulsion simultaneously meeting these requirements, i.e., high concentration of silicone while retaining low viscosity, dispersibility, storage stability, and having good antifoam properties.

[0015] Another essential object of the present invention is to provide a method for inhibiting foam formation using a concentrated, low viscosity silicone antifoam emulsion which is dispersible, storage stable and has good antifoam properties. [Means for solving the problem]

[0016] These objects are in particular to provide a silicone-in-water antifoam emulsion EA, Volume mean diameter d EA1 At least a first silicone-in-water antifoam emulsion EA1 having a particle size of 6 μm or more and comprising the following components (a) to (e): (a) at least one silicone antifoam agent AS containing 0.1% to 10% by weight of at least one mineral filler C, (b) optionally, at least one organopolysiloxane B1, (c) at least one emulsifier D1, (d) at least one additive F1, (e) water W1, and Volume mean diameter d E2 d EA1 at least a second silicone-in-water emulsion E2 This is achieved by the present invention in relation to a silicone-in-water antifoam emulsion EA comprising:

[0017] The present invention also relates to a method for the preparation of a silicone-in-water antifoam emulsion EA, characterized in that it comprises the following essential steps: (a) dispersing, with stirring, at a temperature above 50° C. and below 75° C., at least one silicone antifoam agent AS, optionally at least one organopolysiloxane B1, at least one emulsifier D1 and a first portion of water until the mixture is homogenized; (b) cooling the mixture obtained at the end of step (a) to a temperature below 30° C. while stirring, adding a second portion of water and then additive F1, stirring the mixture until homogenized to obtain EA1; (c) Add the silicone-in-water emulsion E2 to the EA1 and stir until the antifoam emulsion EA is completely homogenized.

[0018] The present invention also relates to a method for inhibiting foam formation by adding Antifoam Emulsion EA to the liquid surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Silicone-in-water antifoam emulsion EA is Volume mean diameter d EA1 At least a first silicone-in-water antifoam emulsion EA1 having a particle size of 6 μm or more and comprising the following components (a) to (e): (a) at least one silicone antifoam agent AS containing 0.1% to 10% by weight of at least one mineral filler C, (b) optionally, at least one organopolysiloxane B1, (c) at least one emulsifier D1, (d) at least one additive F1, (e) water W1, and Volume mean diameter d E2 d EA1 at least a second silicone-in-water emulsion E2 and wherein the silicone-in-water antifoam emulsion EA has a water content of less than 65% by weight, preferably less than 60% by weight, preferably less than 55% by weight.

[0020] The silicone-in-water antifoam emulsion EA is characterized by having a viscosity of less than 6000 mPa·s, preferably less than 3500 mPa·s.

[0021] All viscosities referred to in this disclosure correspond to the dynamic viscosity at 25° C., called “Newton”, i.e. the magnitude of the dynamic viscosity measured in a manner known per se using a Brookfield viscometer, at shear rate gradients sufficiently low that the measured viscosity is independent of the shear rate gradient.

[0022] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterised in that the content of silicone-in-water emulsion E2 is between 2% and 30% relative to the total weight of the silicone-in-water antifoam emulsion EA, preferably between 2.5% and 30%, more preferably between 4% and 24%, even more preferably between 6% and 20% relative to the total weight of the silicone-in-water antifoam emulsion EA.

[0023] According to another embodiment, the silicone-in-water antifoam emulsion EA is a silicone-in-water emulsion E2 having a volume average diameter d E2 The emulsion is characterized by having the following formula:

[0024] The average particle size of the particles is measured by laser granulometry. The average particle size of the particles corresponds to the diameter D[4,3], which is the volume average diameter. The definition of the volume average diameter D[4,3] is well known to those skilled in the art.

[0025] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that the silicone-in-water emulsion E2 is a silicone-in-water emulsion having a silicone concentration of more than 35% by weight relative to the total weight of E2.

[0026] According to another preferred embodiment, the silicone-in-water antifoam emulsion EA is characterized in that the silicone-in-water emulsion E2 comprises the following components: 35 to 80 parts by weight of at least one organopolysiloxane B2, 0.1 to 10 parts by weight of at least one emulsifier D2, 0 to 5 parts by weight of at least one additive F2, and · 5 to 65 parts by weight of water W2 per 100 parts by weight of the total of components B2, D2, F2 and W2.

[0027] The volume average diameter D[4,3] of the emulsion EA1 is preferably more than 6 μm, more preferably from 7 to 150 μm, preferably from 10 to 120 μm.

[0028] Volume average diameter dEA1 The silicone-in-water antifoam emulsion EA1 with a volume average diameter d E2 d EA1 By adding less than 1000 g of silicone-in-water emulsion E2, a silicone-rich, low-viscosity emulsion can be obtained at the same time, thus providing productivity savings and facilitating handling and transportation while retaining good antifoam properties.

[0029] The silicone-in-water antifoam emulsion EA according to the present invention simultaneously has a silicone content of more than 35%, a viscosity of less than 6000 mPa·s, preferably less than 3500 mPa·s, good water dispersibility, good storage stability and good antifoam properties.

[0030] Silicone Emulsion E2 is a silicone-in-water emulsion based on organopolysiloxane.

[0031] To describe organopolysiloxanes, reference is made to the siloxyl units M, D, T and Q. The symbol M is a group represented by the formula (R) 3 SiO 1 / 2 The symbol D represents a difunctional unit (R) in which the silicon atom is bonded to two oxygen atoms in the polymer that contains this unit. 2 SiO 2 / 2 The symbol T represents a silicon atom bonded to three oxygen atoms of the formula (R)SiO 3 / 2 The symbol Q represents a trifunctional unit of the formula SiO 4 / 2 The symbol R represents a tetrafunctional unit of the formula R 2 , R 3 and R 4 The units M, D, and T may be functionalized. The units M, D, and T are described below with specific groups identified.

[0032] The silicone-in-water emulsion E2 comprises at least one organopolysiloxane B2, which can be selected from the group consisting of: per molecule, there are 100,0 ... 1 ~C 40 Alkyl, C 3 ~C 8 Cycloalkyl, C 6 ~C 10 Aryl and C 7 ~C 50 a non-reactive organopolysiloxane having a monovalent organic substituent selected from the group consisting of alkylaryl groups; · reactive organopolysiloxanes containing at least two ≡SiOH silanol groups per molecule; · and mixtures thereof.

[0033] In the present invention, the term "non-reactive" is understood to mean an organopolysiloxane that does not chemically react with any of the constituents of the emulsion under the conditions of emulsification and preparation and use of the silicone-in-water emulsion.

[0034] The non-reactive organopolysiloxane may be an oil or a gum and preferably has a dynamic viscosity of 50 to 600,000 mPa·s at 25°C or a consistency of 200 to 2000 expressed in tenths of a millimeter at 25°C.

[0035] The dynamic viscosity of the silicone is measured at 25° C. according to ASTM D445.

[0036] The term "gum" is conventionally used for organopolysiloxane compounds having a viscosity greater than about 600,000 mPa·s (which corresponds to a molecular weight greater than 260,000 g / mol).

[0037] The viscosity or permeability of the gums is measured at 25° C. by a penetrometer of type PNR12 or equivalent model which makes it possible to apply a cylindrical head to the sample under standardized conditions.

[0038] The permeability of a gum is the depth, in tenths of a millimeter, that a calibrated cylinder will penetrate with a sample in one minute.

[0039] For this purpose, a sample of gum is introduced into an aluminium cup with a diameter of 40 mm and a height of 60 mm. A bronze or brass cylindrical head with a diameter of 6.35 mm and a length of 4.76 mm is fitted with a metal rod with a length of 51 mm and a diameter of 3 mm, which fits into the penetrometer. This rod is loaded with a load of 100 g. The total weight of the assembly is 151.8 g (including the cylindrical part and its supporting rod, 4.3 g). The cup with the gum sample is placed in a thermostatic bath at 25 ± 0.5 °C for at least 30 minutes. The measurements are carried out according to the manufacturer's instructions. The values ​​of the depth (V), expressed in tenths of a millimetre, and the time (t) to reach this depth, expressed in seconds, are displayed on the instrument. The penetration is equal to 60 V / t, expressed in tenths of a millimetre per minute.

[0040] The non-reactive organopolysiloxane gums that can be used according to the invention are used alone or in a mixture in an inorganic solvent, which can be chosen from volatile silicones, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), polydimethylsiloxane (PDMS) oils, polyphenylmethylsiloxane (PPMS) oils, or mixtures thereof, making it possible to avoid the use of organic solvents that are harmful to the environment and to the health of workers in tire manufacturing plants.

[0041] Advantageously, the non-reactive organopolysiloxane is a linear non-reactive organopolysiloxane oil which is a linear homopolymer or copolymer. Preferably, the linear non-reactive organopolysiloxane oil has a dynamic viscosity in the range of 0.65 to 100000 mPa·s at 25° C. Examples that may be mentioned include linear organopolysiloxanes, which are Along each strand, (i) optionally dissolving the formula (R 5 ) 2 SiO 2 / 2 The formula R combined with units of 5 R 6SiO 2 / 2 With units of (ii) optionally, a compound of the formula (R 5 ) 2 SiO 2 / 2 The formula (R 6 ) 2 SiO 2 / 2 With units of (iii) optionally, a compound of the formula (R 5 ) 2 SiO 2 / 2 The formula R combined with units of 5 R 6 SiO 2 / 2 Units and formulas of (R 6 ) 2 SiO 2 / 2 It is composed of units of At the end of each chain, the formula (R 7 ) 3 SiO 1 / 2 (In the formula, R 7 The groups may be the same or different, R 5 and R 6 is blocked by a unit selected from the group Where R 5 and R 6 The groups are monovalent organic substituents of the various siloxyl units described above and have the following definitions: (a)R 5 The groups may be the same or different and are selected from: 1. Linear C 1 ~C 6 Or branch C 3 ~C 6 Alkyl groups, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, n-pentyl or n-hexyl, and 2.C 3 ~C 8 cycloalkyl groups, such as cyclopentyl or cyclohexyl; (b)R 6 The groups may be the same or different and are selected from: 1.C 6 -C10 aryl groups, such as phenyl or naphthyl; 2.C 7 ~C15 Alkylaryl groups, such as tolyl or xylyl, and 3.C 7 ~C 15 Arylalkyl groups, for example benzyl.

[0042] The reactive organopolysiloxane may be an oil or a gum and preferably has a dynamic viscosity of 50 to 600000 mPa·s at 25°C or a consistency of 200 to 2000 expressed in tenths of a millimeter at 25°C.

[0043] Preferably, the reactive organopolysiloxane of the silicone-in-water emulsion E2 comprises the following siloxyl units: M OH =[(OH)(R 2 ) 2 SiO 1 / 2 ] and D=[R 3 R 4 SiO 2 / 2 ] During the ceremony, R 2 , R 3 and R 4 are the same or different groups selected from the group consisting of: Linear or branched C 1 ~C 6 Alkyl groups, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, n-pentyl or n-hexyl; C 3 ~C 8 Cycloalkyl groups, such as cyclopentyl or cyclohexyl; C 6 ~C 10 aryl groups, such as phenyl or naphthyl, and C 7 ~C 15 Alkylaryl groups, such as tolyl or xylyl.

[0044] Silicone-in-water emulsion E2 also contains an emulsifier D2. The nature of emulsifier D2 can be easily determined by one skilled in the art, but the objective is to produce a stable emulsion. Anionic, cationic, nonionic and zwitterionic surfactants can be used, either alone or in mixtures.

[0045] It should be noted that the silicone-in-water emulsion E2 may also contain a protective colloid such as polyvinyl alcohol, as described in EP-A-0 946 240.

[0046] Anionic surfactants include the following surfactants: ·Formula R a -CH(SO 3 M)COOR b wherein R a is C 8 ~C 20 , preferably C 10 ~C 16 R represents an alkyl group. b is C 1 ~C 6 , preferably C 1 ~C 3 where M represents an alkali metal (sodium, potassium, lithium) cation, a substituted or unsubstituted ammonium (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium) cation, or a cation derived from an alkanolamine (monoethanolamine, diethanolamine, triethanolamine), ·Formula R c OSO 3 M alkyl sulfate (wherein R c is C 10 ~C 24 , preferably C 12 ~C 20where M represents a hydrogen atom or a cation having the same definition as above, as well as their ethoxylated (EO) and / or propoxylated (PO) derivatives, preferably having 1 to 20 EO units; ·Formula R d CONHR e OSO 3 M alkyl amide sulfate (wherein R d is C 2 ~C 22 , preferably C 6 ~C 20 R represents an alkyl group. e is C 2 ~C 3 and M represents a hydrogen atom or a cation having the same definition as above, as well as their ethoxylated (EO) and / or propoxylated (PO) derivatives, preferably having 1 to 20 EO units; Saturated or unsaturated C 8 ~C 24 , preferably C 14 ~C 20 Salts of fatty acids, C 9 ~C 20 Alkylbenzenesulfonates and their ethoxylated (EO) and / or propoxylated (PO) derivatives, preferably those having 1 to 20 EO units; C 9 ~C 20 Alkylbenzene sulfonate, primary or secondary C 8 ~C 22These are alkyl sulfonates, alkyl glycerol sulfonates, sulfonated polycarboxylic acids as described in GB 1082179, paraffin sulfonates, N-acyl-N-alkyl taurates, mono- and dialkyl phosphates, alkyl isethionates, alkyl succinates, alkyl sulfosuccinates, sulfosuccinic acid mono- or diesters, N-acylsarcosinates, alkyl glycoside sulfates, polyethoxy carboxylates, the cation being an alkali metal (sodium, potassium or lithium), a substituted or unsubstituted ammonium residue (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium) or an alkanolamine derivative (monoethanolamine, diethanolamine or triethanolamine).

[0047] Examples of nonionic surfactants include poly(alkylene oxide) alkyl or aryl ethers, polyoxyethylene sorbitan hexastearate, polyoxyethylene sorbitan oleate, and poly(ethylene oxide) cetyl stearyl ether. Examples of poly(alkylene oxide) aryl ethers include polyoxyethylene alkylphenols. Examples of poly(alkylene oxide) alkyl ethers include polyethylene glycol isodecyl ether and polyethylene glycol trimethylnonyl ether, which contain 3 to 15 ethylene oxide units per molecule.

[0048] Examples of surfactants that may be mentioned include, for example, ionic, non-ionic or amphoteric fluorinated surfactants and mixtures thereof, such as, for example: Perfluoroalkyl, Perfluorobetaine, Ethoxylated polyfluoroalcohols, Ammonium polyfluoroalkyl, The hydrophilic portion comprises one or more saccharide units having 5-6 carbon atoms and the hydrophobic portion has the formula R f (CH 2 ) n- (wherein n=2 to 20, R f is the formula C m F 2m+1 and m=1 to 10. Polyelectrolytes with fatty perfluoroalkyl side groups.

[0049] The term "fluorinated surfactants", as fully known per se, is understood to mean compounds composed of an aliphatic perfluorocarbon part having at least 3 carbon atoms and an ionic, nonionic or amphoteric hydrophilic part. The perfluorocarbon part having at least 3 carbon atoms can represent all or only part of the fluorocarbon part of the molecule. There is a large literature on this type of compound. The skilled person may refer in particular to the following documents: · FR 2 149 519, WO 94 / 21233, US 3 194 767, The book Fluorinated Surfactants, Erik Kissa, published by Marcel Dekker Inc (1994) Chapter 4, especially Tables 4.1 and 4.4.

[0050] In particular, mention may be made of the products sold by DuPont under the name Zonyl®, such as FSO, FSN-100, FS-300, FSD, fluorinated surfactants sold by DuPont under the name Forafac®, and products sold by 3M under the name Fluorad®.

[0051] Among these surfactants, mention may be made in particular of the anionic, cationic, nonionic and amphoteric perfluoroalkyl compounds, especially the Zonyl® class of surfactants sold under the names Zonyl® FSA, Zonyl® FSO, Zonyl® FSC and Zonyl® FSK by DuPont.

[0052] You can also specify in this regard: Zonyl® FSO100: CAS 65545-80-4, (non-ionic) 99% to 100%, balance 1,4-dioxane, Zonyl® FSN: CAS 65545-80-4, 99% to 100%, with the remainder being sodium acetate and 1,4-dioxane. Zonyl® FS-300: CAS 65545-80-4, 40%, with the remainder being 1,4-dioxane (less than 0.1%) and water. · Zonyl® FSD: CAS 70983-60-7 30%, (cationic), balance hexylene glycol (10%), sodium chloride (3%) and water (57%).

[0053] Also included are: Perfluoroalkyl betaines (amphoteric), such as the product sold by DuPont under the name "Forafac® 1157", ethoxylated polyfluoroalcohols (non-ionic), such as the product sold by DuPont under the name "Forafac 1110 D", polyfluoroalkyl ammonium salts (cationic), such as the product sold by DuPont under the name "Forafac 1179", The hydrophilic portion comprises one or more saccharide units containing 5-6 carbon atoms (units derived from sugars such as fructose, glucose, mannose, galactose, talose, gulose, allose, altose, idose, arabinose, xylose, lyxose and / or ribose) and the hydrophobic portion has the formula R F (CH 2 ) n (wherein n may range from 2 to 20, preferably from 2 to 10; R F is the formula C m F 2m+1 (m may range from 1 to 10, preferably from 4 to 8) represents a perfluoroalkyl unit of the formula R F (CH2 ) n C(O), where n may range from 2 to 10, and R F is the formula C m F 2m+1 where m may range from 4 to 8 and is selected from those described in Journal of the American Oil Chemists' Society (JAOCS), Vol. 69, No. 1, January 1992, and having the characteristics defined above; and ·R F (CH 2 ) n (wherein n may range from 2 to 20, preferably from 2 to 10; R F is the formula C m F 2m+1 where m may range from 1 to 10, preferably from 4 to 8) groups, and having the characteristics defined above; 2 C 7 F 15 The polyacrylates having the groups are selected from those having the characteristics defined above.

[0054] The amount of emulsifier D2 depends on the type of each component present and on the nature of the emulsifier used. As a rule, the emulsions contain from 0.1% to 10% by weight of emulsifier relative to the total weight of the emulsion.

[0055] Furthermore, in a non-limiting manner, additives F2 such as film-forming polymers, biocides, rheology modifiers, coalescers, dispersants, acidifiers, neutralizing agents, bases and / or thickeners can also be used in the emulsion, either alone or in mixtures.

[0056] The concentrations of such adjuvants are known to those skilled in the art.

[0057] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that the silicone antifoam agent AS is obtained by polycondensation chemistry.

[0058] Said polycondensation chemistry is well known to those skilled in the art and may be found, without being limited thereto, in the documents EP-A-0163541 and EP-A-2794760.

[0059] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterised in that the silicone antifoam agent AS is obtained by polyaddition chemistry.

[0060] Said polyaddition or hydrosilylation chemistry is well known to those skilled in the art. Non-limiting examples include EP 0434060, US 8053480, WO 2018 / 224131 and WO 2021 / 167728.

[0061] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that the silicone antifoam agent AS is obtained by radical chemistry.

[0062] The radical chemistry is well known to those skilled in the art. For example, but not limited to, reference may be made to International Publication No. WO 2021 / 126195.

[0063] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that the silicone antifoam agent AS is obtained by mixing various silicone antifoam agents AS.

[0064] The mineral filler C of the silicone antifoam agent AS is a compound selected from the group consisting of silica, preferably fumed and / or precipitated and / or colloidal silica, diatomaceous earth, ground quartz, calcium carbonate, hydrated alumina, magnesium hydroxide, carbon black, titanium dioxide, aluminum oxide, vermiculite, zinc oxide, mica, talc, iron oxide, barium sulfate, hydrated lime, and mixtures thereof. The mineral filler C of the silicone antifoam agent AS is preferably silica.

[0065] It may be treated or untreated precipitated silica or fumed silica. The precipitated silica may be pre-hydrophobized, preferably by conventional treatment with one or more organosilicon compounds. It may also be formulated untreated and treated (hydrophobized) in situ with one or more organosilicon compounds. Such compounds include methylpolysiloxanes such as hexamethyldisiloxane and octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane and hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane and dimethylvinylchlorosilane, and alkoxysilanes such as dimethyldimethoxysilane. During this treatment, the silica may gain up to 20% of its initial weight. Fumed silica may also be used untreated, although it may be treated, if necessary, in the same way as precipitated silica.

[0066] The mineral filler C generally has a specific surface area, measured according to the BET method, of at least 10 m 2 / g, especially 20-300m 2 / g. Mixtures of fillers C may also be used.

[0067] The content of the mineral filler C is generally 0.1% to 10% by weight of the silicone antifoam agent AS, preferably 0.5% to 10% by weight of the silicone antifoam agent AS.

[0068] Silicone antifoam AS or silicone-in-water antifoam emulsion EA1 may contain polyether silicone to improve the properties of the antifoam. The latter is well known to those skilled in the art. Examples include, but are not limited to, the following documents: WO 2020 / 228212, EP 3423165, EP 2563491 and EP 2563491.

[0069] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that it comprises a silicone-in-water antifoam emulsion EA1 having a water content of less than 65% and a silicone-in-water emulsion E2 having a water content of less than 65%.

[0070] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that the particle size distribution of the dispersed silicone phase is bimodal with a ratio of the proportion of coarse particles / the proportion of fine particles of 98 / 2 to 60 / 40, the proportion of coarse particles being calculated in the following manner: (weight of silicone antifoam agent AS+weight of organopolysiloxane B1+weight of emulsifier D1) of antifoam emulsion EA1 / (sum of (weight of silicone antifoam agent AS+weight of organopolysiloxane B1+weight of emulsifier D1) and (weight of solids of emulsion E2)) of antifoam emulsion EA1, the proportion of fine particles being the remainder to 100%.

[0071] Preferably, the ratio of coarse particles to fine particles in the antifoam emulsion EA is 98 / 2 to 70 / 30.

[0072] According to another embodiment, the silicone-in-water antifoam emulsion EA is characterized in that it comprises, relative to 100 parts by weight of the antifoam emulsion EA, the following components: Volume mean diameter d EA1 70 to 98 parts by weight of a silicone-in-water antifoam emulsion EA1 having a particle size of 6 μm or more, comprising the following components (a) to (e): (a) 15 to 55 parts by weight of at least one silicone antifoam agent AS containing 0.1 to 10 parts by weight of at least one mineral filler C, (b) 0 to 25 parts by weight of at least one organopolysiloxane B1, (c) 0.1 to 12 parts by weight of at least one emulsifier D1, (d) 0.01 to 5 parts by weight of at least one additive F1, (e) 3 to 65 parts by weight of water W1, and Volume mean diameter d E2 d EA1 2 to 30 parts by weight of at least a second silicone-in-water emulsion E2.

[0073] Organopolysiloxane B1 may be the same as or different from B2 and may be reactive or non-reactive as described above for B2.

[0074] Emulsifier D1 may be the same as or different from D2. Protective colloids such as polyvinyl alcohol or nonionic, anionic or cationic surfactants may be used alone or in mixtures.

[0075] Additive F1 may be the same as or different from F2.

[0076] Another subject of the invention relates to a process for the preparation of a silicone-in-water antifoam emulsion EA, characterized in that it comprises the following essential steps: (a) dispersing, with stirring, at a temperature above 50° C. and below 75° C., at least one silicone antifoam agent AS, optionally at least one organopolysiloxane B1, at least one emulsifier D1 and a first portion of water until the mixture is homogenized; (b) cooling the mixture obtained at the end of step (a) to a temperature below 30° C. while stirring, adding a second portion of water and then additive F1, stirring the mixture until homogenized to obtain EA1; (c) Adding the silicone-in-water emulsion E2 to the EA1 and stirring until the silicone-in-water antifoam emulsion EA is completely homogenized.

[0077] More particularly, the present invention relates to a method for inhibiting foam formation by adding a silicone-in-water antifoam emulsion EA to the liquid surface.

[0078] Other advantages and features of the invention will become apparent on reading the following examples, given by way of illustration and without being in any way limiting. EXAMPLES

[0079] In the following examples, various silicone antifoam agents AS, polydimethylsiloxane silicone oil B1, silicone-in-water emulsion E2 and emulsifier D1 were used to prepare silicone-in-water antifoam emulsions EA according to the present invention. Unless otherwise specified, % is expressed by weight throughout this specification.

[0080] Raw materials used Various commercial defoamers AS with silica contents C ranging from 0.5% to 10% were used: Silcolapse™ 825, sold by Elkem Silicones, is a silicone antifoam AS derived from polycondensation chemistry described in EP 0 163 541; Silcolapse® 120, sold by Elkem Silicones, is a silicone defoamer AS described in U.S. Pat. No. 3,383,327; Silcolapse® 490, sold by Elkem Silicones, is a silicone antifoam AS derived from polycondensation chemistry described in EP-A-0163541.

[0081] Bluesil™ FLD47V350, available from Elkem Silicones, is a non-reactive polydimethylsiloxane silicone oil B1 with a viscosity of approximately 350 mPa·s.

[0082] Bluesil™ FLD48V135000, available from Elkem Silicones, is a reactive (α,ω-dihydroxy) polydimethylsiloxane silicone oil B1 with a viscosity of approximately 135000 mPa·s.

[0083] Various commercial emulsions E2 were used: Bluesil™ Emul 872, sold by Elkem Silicones, is an emulsion E2 of 47V350 non-reactive polydimethylsiloxane silicone oil B2, with a solids content of about 61% and a volume average diameter D[4,3] of 0.16 μm; Bluesil Emul 284 from Elkem Silicones is an emulsion E2 of 48V135000 reactive (α,ω-dihydroxy) polydimethylsiloxane silicone oil B2, contains approximately 51% solids, and has a volume average diameter D[4,3] of 0.26 μm.

[0084] Radiasurf 7145 sold by Oleon is Emulsifier D1: Sorbitan Monostearate.

[0085] MyrjS40 sold by Croda is Emulsifier D1:PEG-40 Stearate.

[0086] Rhodasurf ROX, sold by Solvay, is Emulsifier D2: an ethoxylated branched alcohol.

[0087] Proxel GXL, sold by Lonza, is a solution containing 20% ​​of the additive F1: 1,2-benzisothiazolin-3-one.

[0088] Emulsion properties - Measurement methods: The solids content is expressed as % of the residue and is determined using a halogen moisture meter (1 g - 105°C - 60 min). The viscosity of the emulsion is measured at the start and after one month at 40° C. using a Brookfield viscometer (A4V20). The particle size distribution PSD is measured with a Malvern Mastersizer 3000 Laser Granulometer. D[4,3] corresponds to the volume mean diameter and is expressed in μm. The usability of the emulsion is estimated by filtering through a 250 μm nylon screen. To estimate the dispersibility of an emulsion, a drop of emulsion is dispensed from a pipette into a cylindrical tube 4.5 cm high and 1.4 cm in diameter filled with 3 ml of deionized water. The number of complete inversions required for total dispersibility is quantified. An emulsion is considered dispersible if the number of complete inversions is less than 10, preferably less than 5. Storage stability is checked visually every two months. The number of months after which phase separation is observed is recorded. The antifoam properties are verified using a recirculation test. 800 ml of detergent solution (3 g / l sodium dodecylbenzenesulfonate and an average of 7 times ethoxylated C 12 ~C 18 A solution of 100 g of antifoam emulsion (aqueous solution containing fatty alcohols) is pumped through a 2 liter test specimen at a flow rate of 200 l / h at 60 °C and recirculated. As soon as the foam level reaches the mark H1 in ml, 50 mg of antifoam emulsion is injected and the foam level is monitored over time. First, the foam level drops and the reading of the low point (H2 in ml) makes it possible to calculate the "shock effect" (1-(H2 / H1)), expressed as a percentage.

[0089] Composition and properties of emulsion EA obtained from single silicone antifoam agent AS. [Table 1]

[0090] Example 1 according to the present invention: A glass vessel equipped with an anchor stirrer is charged with 154 g of Silcolapse 825AS, 110 g of Bluesil 47V350B1, 49.5 g of Radiasurf 7145D1, 16.6 g of Myrj S40D1, and 65.1 g of deionized water W1 (first part). Stir at 60 rpm for 45 minutes while heating to 65° C. to dissolve the emulsifiers and homogenize the mixture. Stirring is then increased to 150 rpm over 20 minutes, then the mixture is cooled to 30° C., and at this temperature 329 g of deionized water W1 (second part) is added over 1 hour at a speed of 10 rpm while continuing to cool to room temperature. The stirring speed is increased to 50 rpm and stirred for 25 minutes. 176 g of Bluesil Emul 872 emulsion E2 is then added over 15 minutes. Finally, 1.4 g of Proxel GXLF1 is added and stirring is continued for 15 minutes.

[0091] The resulting concentrated silicone-in-water antifoam emulsion was a white emulsion with a bimodal particle size distribution, a volume average diameter [D(4,3)] of 54 μm, a solids content of 48% and a viscosity of 270 mPa s, i.e., approximately 37 times lower viscosity than Comparative Example 1 at equivalent solids content.

[0092] Unlike Comparative Example 1, the emulsion was easily filtered through a 250 μm screen and was dispersible. The viscosity after 1 month at 40°C is much lower than 3500 mPa·s.

[0093] Comparative Example 1: The procedure of Example 1 was followed, except that Bluesil Emul 872E2 was added and the amounts of each component listed in Table 1 were added. In the absence of Bluesil Emul 872 Emulsion E2, the resulting emulsion had a unimodal particle size distribution, a volume average diameter [D(4,3)] of about 90 μm, and a viscosity of greater than 10000 mPa·s at a solids content equivalent to that of Example 1 according to the invention. Unlike Example 1 according to the invention, this emulsion could not be filtered through a 250 μm screen, dispersibility was poor, and phase separation was observed after 4 months.

[0094] Composition and properties of emulsions EA obtained from mixtures of two silicone antifoam agents AS. [Table 2]

[0095] Examples 2 to 5 according to the present invention: The procedure of Example 1 was followed with the amounts of each component listed in Table 2. Two types of silicone antifoam AS are used in combination, instead of one type. White emulsions were obtained with a bimodal particle size distribution, with a volume average diameter [D(4,3)] of 34-13 μm and a viscosity of less than 6000 mPa·s at a solids content close to 50%, i.e. 2-10 times lower than in Comparative Example 2 at comparable solids content. All emulsions can be filtered through a 250 μm screen, have good dispersibility, i.e. an inversion number of less than 5 times, and a viscosity of less than 6000 mPa·s after 1 month at 40 ° C. No phase separation is observed after storage for 12 months, while they show good antifoam properties: the measured shock effect is more than 89%.

[0096] Comparative Example 2: The procedures of Examples 2 to 5 were followed, with the exception that Emulsion E2 was added, with the amounts of each component listed in Table 2. The resulting emulsion was a very viscous white paste with a unimodal particle size distribution. The volume average diameter was about 70 μm, and the viscosity was greater than 10,000 mPa·s at solids contents comparable to those of Examples 2 to 5 according to the invention. Unlike Examples 2 to 5 according to the invention, this emulsion could not be filtered through a 250 μm screen, had poor dispersibility (>20 inversions), and phase separation was observed after 6 months.

[0097] Composition and properties of emulsions EA obtained from emulsions E2 with different volume average diameters. [Table 3]

[0098] Preparation of emulsion E2: Bluesil Emul284 emulsion: E2 D[4,3]=3.5μm A glass vessel equipped with an anchor stirrer is charged with 195 g of Bluesil FLD 48V135000 oil B2, 16.1 g of Rhodasurf ROXD2, and 6.5 g of deionized water W2 (part 1). Stirring is carried out at 30 rpm for 20 minutes, and then 134 g of deionized water W2 (part 2) is added over 15 minutes. When all the water is incorporated, stirring is maintained at 100 rpm for 15 minutes and 0.5 g of Proxel GXLF2 is added. The resulting silicone-in-water emulsion was a white emulsion with a volume average diameter [D(4,3)] of 3.5 μm and a solids content of 58.5%.

[0099] Bluesil Emul284 emulsion: E2 D[4,3]=5.5μm A glass vessel equipped with an anchor stirrer is charged with 177 g of Bluesil FLD 48V135000 oil B2, 9.6 g of Rhodasurf ROXD2, and 9.0 g of deionized water W2 (part 1). Stirring is carried out at 40 rpm for 10 minutes, and then 157 g of deionized water W2 (part 2) is added over 20 minutes. When all the water is incorporated, stirring is maintained at 100 rpm for 15 minutes and 0.5 g of Proxel GXLF2 is added. The resulting silicone-in-water emulsion was a white emulsion with a volume average diameter [D(4,3)] of 5.5 μm and a solids content of 51.6%.

[0100] Examples 6 to 9 according to the present invention: The procedure of Example 1 was followed with the amounts of each component listed in Table 3. Emulsion E2 with different volume average diameters was used. The white emulsions have a bimodal particle size distribution, a volume average diameter [D(4,3)] between 12.3 and 4.5 μm, a viscosity below 6000 mPa·s at a solids content close to 66%, i.e. 2-7 times lower than Comparative Example 3 at comparable solids content. All emulsions can be filtered through a 250 μm screen, have good dispersibility, i.e. an inversion number of less than 5 times, and a viscosity below 6000 mPa·s after 1 month at 40 ° C.

[0101] Comparative Example 3: The procedure of Examples 6-9 was followed, with the exception that emulsion E2 was added, with the amounts of each component listed in Table 3. The resulting emulsion was a viscous white paste with a unimodal particle size distribution. The volume average diameter was about 70 μm and the viscosity was 9950 mPa·s at a solids content equivalent to Examples 6-9 according to the invention. Unlike Examples 6-9 according to the invention, this emulsion could not be filtered through a 250 μm screen and its dispersibility was poor (9 inversions).

Claims

1. A silicone-in-water antifoam emulsion EA, comprising: Volume average diameter d EA1 At least a first silicone-in-water antifoam emulsion EA1 having a particle size of 6 μm or more and comprising the following components (a) to (e): (a) at least one silicone antifoam agent AS containing from 0.1% to 10% by weight of at least one mineral filler C; (b) optionally, at least one organopolysiloxane B1, (c) at least one emulsifier D1, (d) at least one additive F1, (e) water W1, and Volume average diameter d E2 d EA1 At least a second silicone-in-water emulsion E2 having a molecular weight of less than wherein said silicone-in-water antifoam emulsion EA has a water content of less than 65% by weight.

2. 2. The silicone-in-water antifoam emulsion EA according to claim 1, characterized in that it has a viscosity of less than 6000 mPa·s.

3. 2. The silicone-in-water antifoam emulsion EA according to claim 1, characterized in that the content of said silicone-in-water emulsion E2 is 2%-30% based on the total weight of said silicone-in-water antifoam emulsion EA.

4. The silicone-in-water emulsion E2 has a volume average diameter d E2 2. The silicone-in-water antifoam emulsion EA according to claim 1, which is an emulsion having the formula:

5. 2. The silicone-in-water antifoam emulsion EA according to claim 1, characterized in that said silicone-in-water emulsion E2 is a silicone-in-water emulsion having a silicone concentration of 35% or more by weight of the total weight of E2.

6. The silicone-in-water emulsion E2 from 35 to 80 parts by weight of at least one organopolysiloxane B2, from 0.1 to 10 parts by weight of at least one emulsifier D2, 0 to 5 parts by weight of at least one additive F2, and 5 to 65 parts by weight of water W2 per 100 parts by weight of the total of components B2, D2, F2 and W2 2. The silicone-in-water antifoam emulsion EA according to claim 1, comprising:

7. 2. Silicone-in-water antifoam emulsion EA according to claim 1, characterized in that said silicone antifoam agent AS is obtained by polycondensation chemistry.

8. 2. Silicone-in-water antifoam emulsion EA according to claim 1, characterized in that said silicone antifoam agent AS is obtained by polyaddition chemistry.

9. 2. Silicone-in-water antifoam emulsion EA according to claim 1, characterized in that said silicone antifoam agent AS is obtained by radical chemistry.

10. 2. The silicone-in-water antifoam emulsion EA according to claim 1, characterized in that the silicone antifoam AS is a mixture of a plurality of silicone antifoam AS.

11. 2. The silicone-in-water antifoam emulsion EA according to claim 1, characterized in that it comprises: a silicone-in-water antifoam emulsion EA1 having a water content of less than 65%; and a silicone-in-water emulsion E2 having a water content of less than 65%.

12. The particle size distribution of the dispersed oily phase is bimodal with a ratio of the proportion of coarse particles to the proportion of fine particles of 98 / 2 to 60 / 40, and the proportion of coarse particles is determined by the following method: (weight of silicone antifoam agent AS+weight of organopolysiloxane B1+weight of emulsifier D1) of the silicone-in-water antifoam emulsion EA1 / (sum of (weight of silicone antifoam agent AS+weight of organopolysiloxane B1+weight of emulsifier D1) and (weight of emulsifier E2) of the silicone-in-water antifoam emulsion EA1) The silicone-in-water antifoam emulsion EA according to claim 1, characterized in that the ratio of the fine particles is the remainder relative to 100%.

13. Per 100 parts by weight of antifoam emulsion EA, Volume average diameter d EA1 70 to 98 parts by weight of a silicone-in-water antifoam emulsion EA1 having a particle size of 6 μm or more, comprising the following components (a) to (e): (a) 15 to 55 parts by weight of at least one silicone antifoam agent AS containing 0.1 to 10 parts by weight of at least one mineral filler C; (b) 0 to 25 parts by weight of at least one organopolysiloxane B1, (c) 0.1 to 12 parts by weight of at least one emulsifier D1, (d) 0.01 to 5 parts by weight of at least one additive F1, (e) 3 to 65 parts by weight of water W1, and Volume average diameter d E2 d EA1 2 to 30 parts by weight of at least a second silicone-in-water emulsion E2 The silicone-in-water antifoam emulsion EA according to any one of claims 1 to 12, comprising:

14. Next required step: (a) dispersing, with stirring, at a temperature above 50° C. and below 75° C., at least one silicone antifoam agent AS, optionally at least one organopolysiloxane B1, at least one emulsifier D1, and a first portion of water until the mixture is homogenized; (b) cooling the mixture obtained at the end of step (a) to a temperature below 30° C. with stirring, adding a second portion of water and then additive F1, stirring the mixture until homogenized to obtain EA1; (c) adding silicone-in-water emulsion E2 to EA1 and stirring until the silicone-in-water antifoam emulsion EA is completely homogenized; 2. A method for producing the silicone-in-water antifoam emulsion EA according to claim 1, comprising:

15. 15. A method for inhibiting foam formation by adding a silicone-in-water antifoam emulsion EA to a liquid surface, characterized in that said silicone-in-water antifoam emulsion EA is as defined in any one of claims 1 to 13 or obtained by the method according to claim 14.

Images